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<head>
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    <title>Document</title>
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<body>
    <script>
        var isUnique = function(str) { 
            let arr = str.split("")
            let flag = true
            
            for (let i=0; i<arr.length; i++) { 
                for (let j=i+1; j<arr.length; j++) { 
                    if (arr[i] == arr[j]) { 
                        flag = false
                        break
                    }
                }
            }
            return flag
        }
        console.log(isUnique("leecode"))
    
    </script>
</body>
</html>       